What do we call a sudden increase in the severity of a disease?

The term used to describe a sudden increase in the severity of a disease is "exacerbation." This refers specifically to the worsening of a disease or the re-emergence of symptoms after a period of improvement or stability. Understanding this term is crucial in the context of chronic illnesses, where patients may experience fluctuations in their health status.

In cases of exacerbation, symptoms can become more pronounced, requiring medical intervention or adjustments in treatment. Recognizing this change not only helps in managing the condition effectively but also aids in communication between healthcare providers and patients regarding the status of the disease.

Other terms provided in the options have different meanings. "Remission" refers to a period during which the disease is not active or shows significant improvement. The "acute phase" typically describes the initial onset or serious stage of a disease rather than a sudden worsening after a stable phase. "Complication" refers to an additional medical problem that arises from an existing condition, rather than an increase in severity of the disease itself. Therefore, "exacerbation" is the most accurate term for this phenomenon.